Heater for fluids providing zone heating

ABSTRACT

An updraft form of fluid heater having a continuous fluid heating conduit formed from the interconnecting of a plurality of spaced-apart and inverted U-tube sections that are positioned transversely across the interior of the heater. Burners are spaced longitudinally along the central and lower portion of the heater to provide for radiant heating to the fluid conduit and, as desired, spaced transverse partitioning walls in the interior of the heater between certain of the spaced burners provide for maintaining controlled &#39;&#39;&#39;&#39;zone heating&#39;&#39;&#39;&#39; to the fluid carrying through the special continuous radiantly heated conduit section.

United States Patent lnventor Marion W. Barnes Glenview, Ill.

Appl. No. 855,324

Filed Sept. 4, 1969 Patented Mar. 2, 1971 Assignee Universal Oil Products Company Des Plaines, Ill.

HEATER FOR FLUIDS PROVIDING ZONE HEATING [56] References Cited UNITED STATES PATENTS 2,479,544 8/1949 Schauble 122/356X 2,964,033 12/1960 Throckmorton et a]. l22/356X 3,240,204 3/1966 Wiesenthal l22/356X Primary Examiner-Kenneth W. Sprague Attorneys-James R. Hoatson, Jr and Philip T. Liggett ABSTRACT: An updraft form of fluid heater having a continuous fluid heating conduit formed from the interconnecting of a plurality of spaced-apart and inverted U-tube. sections that are positioned transversely across the interior of the heater. Burners are spaced longitudinally along the central 4 Chums 4 Drawing Figs and lower portion of the heater to provide for radiant heating US. Cl 122/240, to the fluid conduit and, as desired, spaced transverse partil22/276 tioning walls in the interior of the heater between certain of Int. Cl. F22b 21/30 the spaced burners provide for maintaining controlled zone Field of Search 122/240, heating to the fluid carrying through the special continuous 276, 356; 126/109 radiantly heated conduit section.

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PATENIED MAR 2|s1| SHEET 1 BF 2 /V VEN TOR Marion W. Barnes A TTOR/VEYS PATENIEU MR 2 I97! SHEU 2 BF 2 Figure 4 I //VVENTOR$-' Mar/on W Barnes BY.-

A TTOfP/VEYS HEATER liLUlDS PROVIDING ZONE HEATING The present invention relates to an improved form of fluid heater of the rectangular updraft type that is particularly designed and arranged to provide controlled radiant heating to a continuous fluid conduit which carries a fluid stream aiong the length thereof. More specifically, the heater utilizes a special form of fluid conduit provided from interconnected and transversely positioned U-tube sections that are spaced along the length of the heater in the radiant heating section. in another aspect the heater provides for selectively positioned partitioning means between spaced burners to effect a controlled heat input to the fluid carrying through theradiantiy heated fluid conduit sections.

Generally, in fluid heaters such as used in the petroleum and chemical industries, the box or rectangular form of heater and the center-wall updraft type of heater incorporates one or more banks of tubes along the different wall surfaces in a manner to receive radiant heat from a suitable heat source. In the center-wall heater, a row of burners fire against each side of a longitudinal center partitioning wall and resulting radiant heat is supplied to tubes positioned along each sidewall. Usually, the tubes in each bank or coil are horizontal and are supported by tube support brackets extending through the sidewalls of the heater, although, in certain designs, the tube banks or coils have tubes which are vertical such that tubes are hung from a roof section or are supported from means adjacent the floor of the heater. One advantage of vertical tubes is the easier accommodation of expansion movements and the elimination of support brackets. Also, it is to be noted that horizontal conduits have a sag or warpage problem due to the usually rather wide spacings between support means and the loss of structural strength of each tube under high temperature heater conditions which may be of the order l,000 F. to l,600 F., or more.

in connection with the present improved heater design, it may be considered a principal object of the invention to provide a fluid heating coil for the radiant heating section thereof which is formed of interconnected and spaced-apart inverted U-tube sections and to provide for the suspended support of the continuous conduit or coil from the top center portion of the heater.

it is also an object of the present invention to provide for central burners and spaced partitioning along the length of the heater such that controlled zone heating may be provided to a fluid stream progressing serially through the plurality of spaced and connected inverted U-tube sections.

in a broad aspect, the present invention provides a heater for fluids, which comprises in combination, a rectangular form of heating chamber defined by side and end walls and an upper roof section, a plurality of spaced-apart inverted U-tube conduit sections positioned transversely across the interior of the heating chamber, with said conduit sections having their opposing straight tubular portions projecting downwardly and interiorly adjacent the opposing sidewalls of such heating chamber, means connecting lower end portions of adjacent conduit sections one to another to provide for a continuing fluid flow through at least a portion of the length of the heater, burner means spaced longitudinally along the central lower portion of said heating chamber to provide a centrally located radiant heat source for each of said inverted U-tube conduit sections, means to remove hot combustion gases from the upper roof section of said heating chamber, and fluid inlet and outlet means connecting to said interior conduit sections to provide for the flow of at least one fluid stream to be heated through said heater.

Each U-tube section is connected through one of the lower vertical leg sections to a next adjacent U-tube section by means of a return-bend or other tube connector means such that the fluid flow passes serially through a plurality of sections in a crisscross manner as well as through the length of the heater chamber. At the same time, the vertical leg positions of the U-tube sections will be subjected to radiant heating from centrally positioned burner means while the upper curved, crossover portion of each inverted U-tube section will be subjected to both radiant heat and high temperature convection heating from the burner means.

Various types of rectangular combustion chambers may be utilized; however, preferably the heater chamber will have an upper longitudinally extending convection gas outlet section and a hip-roof section extending from each of the upper sidewall portions in the manner of a typical center-wall updraft heater. As a result, the side curved portions of each inverted U-tube section can be placed closely adjacent the opposing hip-roof sections of the heater chamber.

The utilization of hanging U-tube sections, is, of course, of particular advantage in providing for the accommodation of the expansions and contractions of the conduit sections under high temperature conditions, with all of the expansion or contracting movement preferably taking place at the lower extremity of each vertical leg portion of the U-tube sections. Tube-support beams and/or hanger means are provided from a central and upper portion of the heater so that the entire weight of the fluid conduit (comprising the plurality of interconnected U-tube sections) will be supported from spaced points along the central portions of at least a portion of the curved sections'Thus, each depending leg section is permitted to hang and be within an expansible-contractable position by the use of guide means rather than support means. As a result, weight supporting brackets along the sidewall portions of the heater are unnecessary and may be eliminated from the conventional arrangement of supporting horizontal sidewall tube arrangements.

In a modified embodiment of a heater of the present form, there may be spaced transverse partitioning walls independent zone heating along varying portions of the heater chamber. In other words, with controlled firing of burner means spaced longitudinally along the central lower portion of the heating chamber, there may be more intense firing of a first series of the burners than there is through a second series of burners in a different section of the heater that is screened from the first series of burners by a partitioning wall. The partitioning may be of refractory brick or other suitable heat resistant wall means capable of withstanding high temperature conditions in the interior of the heater chamber. It is' not necessarily novel to have different heat inputs to different portions of a heater; however, in connection with the present design utilizing the interconnected transverse U-tube coil sections, there is a fluid conduit arrangement that is particularly adapted to having different sections or spaced portions along a continuous length thereof be located in different heat-input zones of the heating chamber.

Various means may be provided for controlling heat input to the different sections of the heater; however, generally, this is carried out by utilizing spaced individual burners and an individual control for each of the burners. At the same time there may be automatic valving means for the burner fuel lines and thermostat controls in different sections of the heater, all in combination with the transverse partitioning means spaced along the interior of the heater, such that heat input to one zone will not have a blending effect on an adjacent zone of the heater.

Reference to the following drawings and the descriptions thereof will serve to set forth the construction and operation of one embodiment of the improved heater design with the special fluid conduit means, as well as point out advantageous features that may be obtained in connection therewith.

DESCRlPTlON OF THE DRAWING MG. 1 of the drawing is a sectional elevational view of an updraft form of heater, using interconnected inverted U-tube sections, in accordance with the present invention.

FIG. 2 is a partial sectional plan view, as indicated by the line 2-2 in FIG. 1, showing spaced transverse partitioning wall means.

FIG. 3 of the drawing is a diagrammatic isometric-type view of a fluid conduit formed from the interconnection of a plurality of spaced, transverse and inverted U-tube sections for use in the radiant heating section of a heater chamber.

FIG. 4 of the drawing indicates, in a partial sectional plan view, the utilization of burner means spaced longitudinally along the center of the floor of the heater in a modified design which eliminates the longitudinal center-wall arrangement requiring the double line of burners.

Referring now particularly to FIGS. 1 and 2 of the drawing, there is indicated a rectangular form heater defined by refractory sidewalls 1 and 1', an end wall 2, and floor sections 3 and 3.

The upper portion of the heater is defined by sloping hipwall sections 4 and 4', as well as by spaced-apart vertical wall sections 5 and 5 which define a central convection heating section 6.

The wall and roof portions of the heater may comprise suspending refractory tile or may be constructed of other refractory materials such as of insulating concrete bonded or otherwise attached to suitable support plates. It is to be pointed out that the heater chamber of the present invention is not to be limited to any one type of material or any one method for constructing the superstructure and the various refractory wall sections in either the radiant or convection heating zones. In this instance, the wall portions are indicated as being supporting from suitable support plate means shown diagrammatically as 7 and 7' which may in turn be respectively supported by spaced sidewall column members 8 and 8'. The latter will in turn be supported from a suitable foundation means 9.

In a similar manner to the lower sidewall portions, the upper hip-roof and wall portions of the heater chamber may be supported from plate means 10 and 10' and from column means 11 and ill. Although not shown in the drawing, the upper spaced wall sections 5 and 5 will have a suitable combustion gas outlet breaching connecting thereto and extending therefrom to in turn connect with a suitable stack means. Thus, the longitudinal and narrow convection section 6 provided between the upper walls 5 and 5' is particularly adapted for the positioning of one or more tube banks of horizontal tubes capable of extracting heat from the hot combustion gases passing from the upper part of the heater chamber to the gas discharge breeching and stock. It is, of course, not intended to limit the present invention to any predetermined number or size of tubes in the convection heating section or to any particular tube arrangement within such section. In other words, the tubes indicated in FIG. 1 of the drawing are merely diagrammatically shown and, at the same time, the tube support beams or plates 12 and 13 which extend transversely across the convection heating section 6 are also diagrammatic and illustrative of one type of support means. However, in accordance with the present invention, the lower transverse tube support means, such as 12, shall each have depending tube support means, such as 14, capable of holding certain of the spaced and inverted U-tube sections 15 which are utilized for the radiant heating of the fluid stream being passed through the lower interior portion of the heater chamber.

As best shown in FIG. 3, the fluid conduit in the radiant heating section of the chamber comprises the interconnecting of a plurality of spaced-apart inverted U-tube sections 15. The upper curved portions are of large radius as that as a result each section has depending vertical leg sections that are adjacent to opposing sidewall portions of the heater chamber. Suitable U-bend sections to may be used at the lower end portions of each tube section 15 to in turn effect the innerconnection of adjacent sections. Thus, as also shown in FIG. 3, the fluid stream to be heated can enter at one end of the continuous fluid conduit, such as at an inlet end 17 and be carried upwardly through a first vertical leg portion and downwardly through an opposing leg portion connected with a return-bend section 16 that in turn connects with a next adjacent U-tube section 15 where it is then carried upwardly and over through a large curved portion to another depending leg section and into a next successive U-bend 16, etc. Thus, there is a continuing sequential flow of the fluid being heated from one inverted U-tube section to another and, also, a flow that actually recrosses from one side of the heater to the other in a plurality of stages as it continues longitudinally down through the length of the heater. At the down-stream end of the fluid conduit means, such as indicated in the plan view of FIG. 2, there may be an exit of the high-temperature radiantly heated stream from the last of a plurality of U-tube sections by way of an outlet means 18.

In a long heater chamber, and in an optional arrangement utilizing more than one fluid conduit in the radiant heating section, there may be two or more fluid heating coils or conduits each of which will have a plurality of interconnected U- tube sections, such as shown in FIG. 3 of the drawing, so as to provide for the heating of more than one fluid stream, each as such stream passes along and through its given portion of the elongated rectangular form heater.

Referring particularly again to FIG. 1 of the drawing, there are shown laterally projecting tube means 19 and 19 as well as 20 and 20'. These guides may be used in conjunction with the upper tube support means 14 to insure the proper positioning and alignment of the entire fluid coil carrying through the one or more heating sections of the heater chamber. Each of the guide means along the sidewall portions of the heater are preferably constructed to merely provide lateral support and not preclude downward and upward movements of the vertical leg portions of the inverted U-tube sections 15 as they expand and contract under the varying temperature conditions within the heater chamber.

It will be noted that the heater embodiment, as shown in FIGS. 1 and 2, provides a longitudinal center-wall portion 21 supported form a suitable central foundation section 22 and that such wall serves to divide the lower portion of the heater chamber into opposing radiant heating sections 23 and 23. The latter, in turn, receive high temperature heating from longitudinally spaced burner means 24 and 24 arranged to tire upwardly through the respective burner block means 25 and 25. In other words, there is provided a typical center-wall updraft type of heater where high-temperature flame impinges across each sidewall portion of the center-wall 21 so as to, in turn, provide high temperature radiant heating to the plurality of tubular members extending down along the internal sidewall portions of the heater chamber.

As a further feature of the present embodiment, each of the burner means 24 and 24 are provided with independent fuel supply lines 26 and 26, as well as control valve means 27 and 27, such that there may be independent control of the firing of each of the burners spaced throughout the length of the heater chamber. Still further, as shown by both FIGS. 1 and 2, there is provided in the present embodiment, the use of a transverse partitioning wall means 28 at one or more zones along the length of the interior of the heater chamber whereby there may be different temperature zones maintained within the heater chamber as controlled by one or more groups of burners with respect to the separation of a next adjacent group of burners. For example, as best shown in FIG. 2, burners 24 and 24' on one side of the partitioning wall 28 may be fired at a different rate than the burners 24-A and 24-A' so as to provide a different heat input to the U-tube sections 15 which are opposite the latter burners as compared to the U-tube sections 15 which are within the zone of burners 24 and 24'. This zone control of heating input to a fluid stream is of particular importance in certain processing operations in order to obtain the desired heating curve for the fluid stream as it passes serially through the multitube coil in the heater chamber from one end to the other or, alternatively, the partitioned zone heating may be of importance to provide separate inputs to separate fluid heating conduits being maintained within the same elongated heater chamber.

It will be noted that the present drawings indicate the partitioning wall 28 to be formed from refractory brick in a typical gravity-wall construction that may be supported from a suitable foundation at the lower portion of the heater chamber. However, in certain types of heaters, or as an alternative type of construction, there may be precast panels of insulating concretes or combinations of insulating concrete and block insulation which may be suitably supported in a vertical manner at the desired partitioning locations. f

With respect to construction aspects and with particular reference to the upper portion of FIG. 1, it is to be noted that each spaced tube-support beam member 12 shall be designed to have ample strength to support one or more U-tube sections 15 from the hanger means 14, as well as carry the load from a given portion of the convection tubes which may pass through and on the top thereof. There are also indicated diagrammatically the use of suitable spaced angles or support members 30 that are attached to the respective structural columns 11 and 11:, as well as the use of support pins or bolt means 31 which shall be capable of carrying the tube loadings from the ends of beam section 12 into the adjacentsupport columns 11 and 11:. The transverse beam sections 12 and center hook arrangement 14 is, of course, particularly adapted for a center-wall updrafi type of heater where there is a centrally positioned convection heating section, such as 6. However, in a modified type of rectangular heater, or a box heater, then a different form of support hook may be provided from suitable roof framing in a manner which will be capable of supporting the weight of the radiant fluid conduit from the plurality of transverse fluid conduit sections 15. It is, of course, not intended to limit the present continuous fluid conduit system in the radiant heating section and the controlled zone heating for such heating conduit to any one form of tube support means as long as the lower vertical leg portions of section 15 are free to expand and contract vertically in'a guided but unhampered heater in that there is the elimination of the center-wall section where burners are fired against the sidewall portions. in other words, the embodiment of FIG. 4 provides spaced burner blocks 32 along the center line of the heater and each block 32 will, in turn, be provided with burner means (not shown) which will have a controlled fuel-input means so that there may be a controlled flame and heat input through each of the longitudinally spaced burner blocks 32 to provide the desired radiant heat for the leg and topcurved portions for each inverted U-tube conduit section 15. FIG. 4 also indicates that there may be one or more transverse partitioning means 33 of refractory brick or other suitable temperature resistant material so that .there may be controlled radiant heating in one radiant heating zone 34 versus a different radiant heat input from a next adjacent controlled heating zone 35. The side and end wall portions of the heater chamber of FIG. 4 may be similar to that illustrated within F IG. 2 of the drawing, and it is not believed to be necessary to repeat the description thereof in connection with the present modified embodiment.

Actually, the burners illustrated, as .well as burner block means, floor construction, structural support means, etc., are

all diagrammatic and should not be considered limiting with respect to use with the present novel fluid conduit construction and with the use of a top support means, nor limiting with respect to the utilization of zone heating for such conduit arrangement providing for the continuously recrossing flow of the fluid stream.

lclaim:

1. A heater for fluids, which comprises in combination, a rectangular form of heating chamber defined by side and end walls and an upper roof section, a fluid conduit of a plurality of spaced-apart inverted U-tube conduit sections positioned transversely across the interior of the heating chamber, with said conduit sections having their opposing straight tubular portions projecting downwardly and interiorly adjacent the opposing sidewalls of such heating chamber and means connecting the lower end portions of adjacent conduit sections one to another to provide for a continuing fluid flow through at least a portion of the length of the heater, burner means spaced longitudinally along the central lower portion of said heating chamber to provide a centrally located radiant heat source for each of said inverted U-tube conduit sections, means to remove hot combustion. gases from the upper roof section of said heating chamber, and fluid inlet and outlet means connecting to said interior fluid conduit sections to provide for the flow of at least one fluid stream to be radiantly heated through said heater.

'2. The heater of claim 1 further characterized in that the upper roof section of said rectangular form heating chamber has a sloping hip-roof section extending along and upwardly from each sidewall portion, together with more closely spaced upper wall sections defining a narrow longitudinal convection heating section, and said fluid conduit of the plurality of spaced-apart inverted U-tube conduit sections is supported from transverse tube support beam sections which extends between said more closely spaced wall sections of the upper portion of the heater chamber.

3. The heater of claim 1 further characterized in that the lower portion of said heater chamber is provided with a longitudinal partitioning center-wall and the burner means spaced longitudinally along the center portion of the heater chamber are in turn positioned each side of said center wall to thereby provide radiant heat from each side thereof to the spaced-apart inverted U-tube conduit sections.

4. The heater of claim 1 further characterized in that at least one transverse partition wall is provided across the interior of the heating chamber and the burner means spaced longitudinally along the center lower portion of said chamber are provided with independent fuel supply means and flow control means whereby there may be different heat outputs from different burner means to resulting variations in heating within different portions of the heating chamber on each side of a transverse partitioning wall. 

1. A heater for fluids, which comprises in combination, a rectangular form of heating chamber defined by side and end walls and an upper roof section, a fluid conduit of a plurality of spaced-apart inverted U-tube conduit sections positioned transversely across the interior of the heating chamber, with said conduit sections having their opposing straight tubular portions projecting downwardly and interiorly adjacent the opposing sidewalls of such heating chamber and means connecting the lower end portions of adjacent conduit sections one to another to provide for a continuing fluid flow through at least a portion of the length of the heater, burner means spaced longitudinally along the central lower portion of said heating chamber to provide a centrally located radiant heat source for each of said inverted U-tube conduit sections, means to remove hot combustion gases from the upper roof section of said heating chamber, and fluid inlet and outlet means connecting to said interior fluid conduit sections to provide for the flow of at least one fluid stream to be radiantly heated through said heater.
 2. The heater of claim 1 further characterized in that the upper roof section of said rectangular form heating chamber has a sloping hip-roof section extending along and upwardly from each sidewall portion, together with more closely spaced upper wall sections defining a narrow longitudinal convection heating section, and said fluid conduit of the plurality of spaced-apart inverted U-tube conduit sections is supported from transverse tube support beam sections which extends between said more closely spaced wall sections of the upper portion of the heater chamber.
 3. The heater of claim 1 further characterized in that the lower portion of said heater chamber is provided with a longitudinal partitioning center-wall and the burner means spaced longitudinally along the center portion of the heater chamber are in turn positioned each side of said center wall to thereby provide radiant heat from each side thereof to the spaced-apart inverted U-tube conduit sections.
 4. The heater of claim 1 further characterized in that at least one transverse partition wall is provided across the interior of the heating chamber and the burner means spaced longitudinally along the center lower portion of said chamber are provided with independent fuel supply means and flow control means whereby there may be different heat outputs from different burner means to resulting variations in heating within different portions of the heating chamber on each side of a transverse partitioning wall. 